Detect domain-specific resolvers on OS X and disable DnsClient in such cases.

third_party/apple_dnsinfo/dnsinfo.h

+/*
+ * Copyright (c) 2004-2006, 2008, 2009 Apple Inc. All rights reserved.
+ *
+ * @APPLE_LICENSE_HEADER_START@
+ * 
+ * This file contains Original Code and/or Modifications of Original Code
+ * as defined in and that are subject to the Apple Public Source License
+ * Version 2.0 (the 'License'). You may not use this file except in
+ * compliance with the License. Please obtain a copy of the License at
+ * http://www.opensource.apple.com/apsl/ and read it before using this
+ * file.
+ * 
+ * The Original Code and all software distributed under the License are
+ * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
+ * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
+ * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
+ * Please see the License for the specific language governing rights and
+ * limitations under the License.
+ * 
+ * @APPLE_LICENSE_HEADER_END@
+ */
+
+#ifndef __DNSINFO_H__
+#define __DNSINFO_H__
+
+/*
+ * These routines provide access to the systems DNS configuration
+ */
+
+#include <Availability.h>
+#include <sys/cdefs.h>
+#include <stdint.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+
+#define DNSINFO_VERSION         20091104
+
+#define DEFAULT_SEARCH_ORDER    200000   /* search order for the "default" resolver domain name */
+
+#define DNS_PTR(type, name)                             \
+        union {                                         \
+                type            name;                   \
+                uint64_t        _ ## name ## _p;        \
+        }
+
+#define DNS_VAR(type, name)                             \
+        type    name
+
+
+#pragma pack(4)
+typedef struct {
+        struct in_addr  address;
+        struct in_addr  mask;
+} dns_sortaddr_t;
+#pragma pack()
+
+
+#pragma pack(4)
+typedef struct {
+        DNS_PTR(char *,                 domain);        /* domain */
+        DNS_VAR(int32_t,                n_nameserver);  /* # nameserver */
+        DNS_PTR(struct sockaddr **,     nameserver);
+        DNS_VAR(uint16_t,               port);          /* port (in host byte order) */
+        DNS_VAR(int32_t,                n_search);      /* # search */
+        DNS_PTR(char **,                search);
+        DNS_VAR(int32_t,                n_sortaddr);    /* # sortaddr */
+        DNS_PTR(dns_sortaddr_t **,      sortaddr);
+        DNS_PTR(char *,                 options);       /* options */
+        DNS_VAR(uint32_t,               timeout);       /* timeout */
+        DNS_VAR(uint32_t,               search_order);  /* search_order */
+        DNS_VAR(uint32_t,               if_index);
+        DNS_VAR(uint32_t,               flags);

[Mark Mentovai, 2013/08/06 15:41:00]

I’m curious why you chose this version of the file from configd-395.7, part of
Mac OS X 10.7.2.

Chrome supports Mac OS X 10.6, and Mac OS X 10.8.x is current. These structures
appear to already have some provisions for compatibility between versions built
in (via the “reserved” fields) so it should be safe to just grab the current
definition of the structure as long as you take care not to use fields that
don’t exist on older systems when running on older systems.

configd-395.7 is neither the configd from the base 10.7 nor the most recent
10.7. It just appears to be some random version.

The current version is
http://opensource.apple.com/source/configd/configd-453.19/dnsinfo/dnsinfo.h.
Generally, just start at http://opensource.apple.com/, pick the OS release
you’re interested in, and then find the source from there.

[szym, 2013/08/06 15:48:58]

395.7 is the newest version that would compile. In patches 1&2 I tried 453.19,
but the availability macro:
__OSX_AVAILABLE_STARTING(__MAC_10_8, __IPHONE_6_0);
would not compile.

+        DNS_VAR(uint32_t,               reserved[6]);
+} dns_resolver_t;
+#pragma pack()
+
+
+#define DNS_RESOLVER_FLAGS_SCOPED       1
+
+
+#pragma pack(4)
+typedef struct {
+        DNS_VAR(int32_t,                n_resolver);            /* resolver configurations */
+        DNS_PTR(dns_resolver_t **,      resolver);
+        DNS_VAR(int32_t,                n_scoped_resolver);     /* "scoped" resolver configurations */
+        DNS_PTR(dns_resolver_t **,      scoped_resolver);
+        DNS_VAR(uint32_t,               reserved[5]);
+} dns_config_t;
+#pragma pack()
+
+
+__BEGIN_DECLS
+
+/*
+ * DNS configuration access APIs
+ */
+const char *
+dns_configuration_notify_key    ()                              __OSX_AVAILABLE_STARTING(__MAC_10_4,__IPHONE_2_0);
+
+dns_config_t *
+dns_configuration_copy          ()                              __OSX_AVAILABLE_STARTING(__MAC_10_4,__IPHONE_2_0);
+
+void
+dns_configuration_free          (dns_config_t   *config)        __OSX_AVAILABLE_STARTING(__MAC_10_4,__IPHONE_2_0);
+
+__END_DECLS
+
+#endif  /* __DNSINFO_H__ */